Official rule text as published in the U.S. Coast Guard Navigation Rules
(g) Vessels of less than 12 meters in length, except those engaged in diving operations, are not required to exhibit the lights or shapes prescribed in this Rule.
(h) The signals prescribed in this Rule are not signals of vessels in distress and requiring assistance. Such signals are contained in Annex IV to these Rules.
MyCOLREGS explanation
Summary
Vessels under 12 meters get a break from all of Rule 27's signals - the two-red not-under-command lights, the red-white-red restricted-ability column, all of it - except when they are engaged in diving operations, which still requires the appropriate signal regardless of size. And a final reminder: none of Rule 27's lights or shapes are distress signals. A vessel in real distress uses the specific signals listed in Annex IV - flares, an ensign flown upside down, SOS, and the like - not a red-white-red column.
Real World Example
Seeing a small boat under 12 meters with no restricted-ability lights doesn't necessarily mean she isn't restricted - she may simply be exempt by size. And if you ever see a vessel showing genuine distress signals (not Rule 27's maneuvering signals), that calls for an entirely different response than simply keeping clear.
Practice Questions
Q1. A 9-meter vessel engaged in restricted-ability work (not diving) shows none of Rule 27's lights or shapes. Under Rule 27(g), is this permitted?
A. No - every vessel regardless of length must show Rule 27's lights and shapes if restricted.
B. Yes - vessels under 12 meters are exempt from Rule 27's lights and shapes, except when engaged in diving operations.
C. No - only vessels under 7 meters get this exemption.
D. Yes, but only on inland waters, never internationally.
Q2. You see a vessel showing Rule 27's red-white-red restricted-ability signal. Under Rule 27(h), should you interpret this as a distress signal?
A. Yes - any unusual light combination should be treated as distress.
B. No - Rule 27's signals are explicitly not distress signals; genuine distress signals are listed separately in Annex IV.
C. Yes, but only if the vessel is also sounding her whistle continuously.
D. No - Rule 27 signals only apply to vessels already in distress.
Practice Question Answers
Q1.
B. Yes - vessels under 12 meters are exempt from Rule 27's lights and shapes, except when engaged in diving operations. Rule 27(g) exempts vessels under 12 meters from this Rule's lights and shapes entirely, with one specific exception: diving operations, which still require the appropriate signal regardless of the vessel's size. A and C misstate the length threshold or deny the exemption outright; D invents an International/Inland difference that doesn't exist here.
Q2.
B. No - Rule 27's signals are explicitly not distress signals; genuine distress signals are listed separately in Annex IV. Rule 27(h) explicitly states that the signals prescribed in this Rule are not distress signals - genuine distress signals are a separate, specific list found in Annex IV. A and C treat Rule 27's ordinary maneuvering signals as distress signals, which the Rule itself explicitly rules out. D has the logic backwards.